The present invention relates to disc drive data storage systems and, more particularly, to a disc head slider for carrying a read/write transducer within a disc drive.
Disc drives are well known in the industry. Such drives use rigid discs, which are coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor, which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g. air) bearing disc head sliders. The sliders carry transducers, which write information to and read information from the disc surfaces.
An actuator mechanism moves the sliders from track-to-track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a suspension for each head gimbal assembly. The suspension includes a load beam and a gimbal. The load beam provides a load force which forces the slider toward the disc surface. The gimbal is positioned between the slider and the load beam, or is integrated in the load beam, to provide a resilient connection that allows the slider to pitch and roll while following the topography of the disc.
The slider has a bearing surface which faces the disc surface. As the disc rotates, the disc drags air under the slider and along the bearing surface in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the bearing surface, air compression along the air flow path causes the air pressure between the disc and the bearing surface to increase, which creates a hydrodynamic lifting force that counteracts the load force and causes the slider to lift and fly above or in close proximity to the disc surface.
One type of slider is a xe2x80x9cself-loadingxe2x80x9d air bearing slider, which includes a leading taper (or stepped-taper), a pair of raised side rails, a cavity dam and a subambient pressure cavity. The leading taper is typically lapped or etched onto the end of the slider that is opposite to the recording head. The leading taper pressurizes the air as the air is dragged under the slider by the disc surface. The cavity dam provides an expansion path for the air to de-pressurize as it is dragged into the sub-ambient pressure cavity by the disc velocity. The expanded air in the cavity provides a self-loading force which forces the slider toward the disc surface. The counteraction between positive pressure developed along the side rails, the preload force provided by the suspension and the self-loading force provides the air bearing with a high vertical stiffness.
The physical separation between the slider and the disc surface at the recording head is an important parameter to disc drive performance. It is desired to minimize variation in the head clearance or xe2x80x9cflying heightxe2x80x9d as the data storage device operated at different altitudes above sea level. It is well known that conventional sliders demonstrate flying height sensitivity to changes in ambient pressure. Specifically, flying height is inversely proportional to operating altitude. Flying height sensitivity to changes in ambient pressure poses severe problems for sliders that are designed to operate at very low flying heights (less than or equal to 1 microinch), since a 20% drop in ambient pressure greatly increases the probability of contact between the slider and the disc surface.
This behavior forces disc drive designers to meet minimum flying height requirements at the highest specified altitude, which is typically 10,000 feet above sea level. As a result, the sliders are designed to fly with an undesirably large head-media spacing at altitudes where the disc drive is most frequently used, i.e., near sea level. Such a design compromise reduces the maximum useable linear density of the storage media and thus the storage capacity of the disc drive.
A slider is therefore desired which has a reduced flying height sensitivity to changes in altitude while being relatively insensitive to manufacturing tolerances. The present invention addresses these and other problems, and offers other advantages over the prior art.
One aspect of the present invention relates to a disc head slider, which includes a longitudinal axis, a recessed region, and first and second elongated rails extending generally parallel to the longitudinal axis and being disposed about the recessed region. Each rail forms a respective bearing surface. First and second elongated depressions extend along the first and second tails, respectively, and each have a depression floor which is recessed relative to the respective bearing surface. First and second convergent channels are recessed within the first and second rails, respectively, relative to the respective bearing surfaces, and include a leading channel end open to fluid flow from the first and second depressions, respectively, channel side walls and a trailing channel end closed to the fluid flow and positioned forward of a portion of the respective bearing surface.
Another aspect of the present invention relates to a disc head slider, which includes a slider body having a leading slider edge, a trailing slider edge and a longitudinal axis extending from the leading slider edge to the trailing slider edge. A recessed area is formed on the slider body and is open to the trailing slider edge. At least one elongated rail extends generally parallel to the longitudinal axis, along the recessed area and forms a bearing surface. A first elongated depression extends along the rail and has a depression floor which is recessed relative to the bearing surface by a first depth. A convergent channel is recessed within the bearing surface and has a leading channel end open to fluid flow from the first elongated depression, channel side walls, a trailing channel end closed to the fluid flow and forward of a portion of the bearing surface, and a channel floor which is recessed relative to the bearing surface by a second depth that is less than the first depth.
Yet another aspect of the present invention relates to a disc drive, which includes a disc and a slider bearing. The disc is rotatable about a central axis and has a recording surface. The slider bearing supports a transducer over the recording surface while directing air flow along rails of the slider bearing means and over a convergent channel feature formed in the rails.